Rocket powered vehicles for use in space missions can generally be categorized into launch systems and payload systems. Launch systems provide the primary thrust for launching the craft from ground and inserting the craft into orbit. Such launch systems include integrated launch vehicles and strap-on boosters. Once in orbit, a payload system such as a satellite, interplanetary probe, or the like may be released. The payload system typically includes propulsion subsystems for orbital maintenance, attitude control, and orbital transfer depending on the application but not for boost into orbit.
Launch systems generally include one or more rocket engines arranged to fire in one or more stages. The engines may use solid fuel and/or liquid fuel. In either case, the engine systems include at least one fuel tank, a combustion chamber and a nozzle for accelerating/discharging the combustion product. The nozzles may be gimballed for controlled thrust vectoring. In the case of liquid fuel rocket engine systems, fuel and oxidizer are generally stored in separate tanks and come into contact in the combustion chamber to provide thrust. Pneumatics are provided for charging the tanks, e.g., on the launch pad so as to reduce transportation risks. Such liquid fuel engines have gained favor for many applications for reasons of performance, economics, safety, throttling capabilities and flexible mission design.
Currently, launch systems are generally built largely without the benefits of mass production techniques and associated efficiencies of scale. In particular, due to the relatively small rate of launch system production, a particular launch system and its component parts are individually fabricated, often using manual or computer numerically controlled machine shop tools. The individual components are then fitted together and assembled. As a result of this individual fabrication process, there can be some degree of variation from component-to-component and system-to-system. Completed assemblies are carefully inspected and tested to achieve the required reliability. It will be appreciated that this process can result in high launch system production costs and a significant barrier to competition. Despite the difficulties and expense of this individual construction process, such a process has been thought necessary due to low production rates and varying mission requirements.